A gas turbine engine generally includes, in serial flow order, a compressor section, a combustion section, a turbine section and an exhaust section. In operation, air enters an inlet of the compressor section where one or more axial compressors progressively compress the air until it reaches the combustion section. Fuel is mixed with the compressed air and burned within the combustion section to provide combustion gases. The combustion gases are routed from the combustion section through a hot gas path defined within the turbine section and then exhausted from the turbine section via the exhaust section.
In particular configurations, the turbine section includes, in serial flow order, a high pressure (HP) turbine and a low pressure (LP) turbine. The HP turbine and the LP turbine each include various rotatable turbine components such as turbine rotor blades, rotor disks and retainers, and various stationary turbine components such as stator vanes or nozzles, turbine shrouds and engine frames. The rotatable and the stationary turbine components at least partially define the hot gas path through the turbine section. As the combustion gases flow through the hot gas path, thermal energy is transferred from the combustion gases to the rotatable turbine components and the stationary turbine components.
In general, the HP turbine and LP turbine may additionally include shroud assemblies which further define the hot gas path. A clearance gap may be defined between the shroud of a shroud assembly and the rotatable turbine components of an associated stage of rotatable turbine components. The shroud is typically retained within the gas turbine engine by a shroud hanger, which in turn is coupled to various other components of the engine. Further, in many cases, nozzles positioned axially forward of a shroud assembly may contact the shroud assembly to define and generally seal the hot gas path.
One issue with many known gas turbine engine designs is load transmission between various adjacent components in various sections of the gas turbine engine. For example, nozzle loads may be transmitted through shroud assemblies into the casing of the gas turbine engine. However, in many cases, it is undesirable for components of shroud assemblies, such as the shrouds themselves, to experience these loads. For example, ceramic matrix composite shrouds, while providing numerous advantages when utilized in gas turbine engines, are generally undesirable for such load transmission due to the characteristics of the ceramic matrix composite material.
One known solution to this load transmission issue is to include an outer support connected to the casing and in contact with the nozzles. Seals are provided between the support and the hanger of the adjacent shroud assemblies. Loads are thus transmitted through the support from the nozzles to the hangers of the shroud assemblies. However, thermal gradients experienced by these supports during operation, and resulting axial deflection of the supports, causes large variations in nozzle-shroud axial gaps. Additional purge flow is thus required to compensate for the potential increases in these axial gap sizes, thus reducing the amount of working fluid utilized for combustion and reducing the efficiency of the engine. Additionally, these supports are generally heavy and expensive parts, thus undesirably increasing the cost and weight of the gas turbine engine.
Accordingly, improved shroud assemblies for use in gas turbine engines are desired. In particular, shroud assemblies having improved load transmission features would be advantageous.